This invention relates to a process for the formation of hydroperoxide derivatives of rubbery polymers via singlet oxygen. Specifically, it relates to a process for the formation of grafted rubbery polymers through the formation of a hydroperoxidized rubbery polymer intermediate.
Prior processes for the production of hydroperoxide derivatives of polymers are known in the art, but have proven unsatisfactory in practice.
U.S. Pat. No. 3,484,353, to Dexter Sharp, discloses such a process. Sharp teaches a method for forming hydroperoxide derivatives of polymers having ethylenic unsaturation in the polymer backbone.
U.S. Pat. No. 3,846,266, to Eduard Duynstee et al., also discloses such a process. Duynstee et al. teach a method for forming hydroperoxide derivatives of polymers having ethylenic unsaturation pendant to the polymer backbone chain.
Both of the cited patents teach the formation of the hydroperoxide derivatives through exposing the polymer to light in the presence of a photosensitizing agent and oxygen. Similarly, both teach that the polymer can be in a dissolved state during the formation of the hydroperoxide derivatives. When forming grafted rubbery polymers, it is particularly desirable to form the hydroperoxide derivatives with the rubbery polymer dissolved directly in the monomers to be grafted thereto. Dissolving the rubbery polymers in the monomers to be grafted thereto prior to forming the hydroperoxide derivatives presents a hitherto unsolved problem. Oftimes, the photosensitizing agent is not sufficiently soluble in the monomers to produce an adequate degree of hydroperoxidation on the rubbery polymer. Neither of the patents teach a method for solubilizing the photosensitizing agent in the monomer/polymer solution. It would be desirable to achieve solubilization of the photosensitizer in the monomer/polymer solution without precipitating the polymer out of solution. It is to this goal that the present invention is directed.